In part two, Professor Al-Khalili looks at the 19th century chemists who struggled to impose an order on the apparently random world of the elements. From working out how many there were to discovering their unique relationships with each other, the early scientists' bid to decode the hidden order of the elements was driven by false starts and bitter disputes. But ultimately the quest would lead to one of chemistry's most beautiful intellectual creations - the periodic table.

In this final episode, Mary Beard delves even deeper into ordinary Roman life by going behind the closed doors of their homes. She meets an extraordinary cast of characters - drunken housewives, teenage brides, bullied children and runaway slaves - and paints a more dynamic, lusty picture of Roman family life. Mary uncovers their preserved beds, furniture and cradles, tries on Roman wedding rings and meets some eccentric wives like Glyconis, praised by her husband for liking a drink or two, and Allia Potestas, who lived in a Roman menage a trois. Mary explores Roman parenting, childbirth and children, including Sulpicius Maximus, an 11-year-old schoolboy who was worked to death by his pushy parents, and Geminia Mater, a 5-year-old tomboy. Finally, Mary paints a more nuanced picture of Roman slavery and asks why if it was such a brutal institution did many Romans choose to be buried with their servants - living cheek by jowl in death, as in life

In the final challenge of the game of life, raising offspring is the ultimate prize. Continuing the line through the next generation, is the next best thing to immortality. But it’s far from easy... Some parents must risk their own lives for their offspring.

Dawkins opines that the moral framework of religions is warped, and argues against the religious indoctrination of children. He discusses specifically the idea of religion seen as a virus in the sense of a meme. He begins by explaining how a child is genetically programmed to believe without questioning the word of authority figures, especially parents – the evolutionary imperative being that no child would survive by adopting a sceptical attitude towards everything their elders said. But this same imperative, he claims, leaves children open to infection by religion.

We will nvestigate the first skeleton that really looks like us –Turkana Boy– an astonishingly complete specimen of Homo erectus found by the famous Leakey team in Kenya. These early humans are thought to have developed key innovations that helped them thrive, including hunting large prey, the use of fire, and extensive social bonds. The program examines an intriguing theory that long-distance running –our ability to jog– was crucial for the survival of these early hominids. Not only did running help them escape from vicious predators roaming the grasslands, but it also gave them a unique hunting strategy: chasing down prey animals such as deer and antelope to the point of exhaustion. Birth of Humanity also probes how, why, and when humans' uniquely long period of childhood and parenting began.

For the animals in the polar regions, autumn means dramatic battles and epic journeys. Time is running out - the Arctic Ocean is freezing over and the sea ice is advancing at 2.5 miles per day around Antarctica. Polar bears gather in large numbers on the Arctic coast as they wait for the return of the ice. Soon, tempers fray and violent sparring contests break out. Meanwhile 2,000 beluga whales head for one special estuary, a gigantic 'whale spa' where they will thrash their snow-white bodies against the gravel and exfoliate. Inland, the tundra undergoes a dramatic transformation from green to fiery red. Here, musk ox males slam head-first into each other with the force of a 30mph car crash as they struggle to defend their harems. Frisky young caribou males play a game of 'grandma's footsteps' as they try to steal the boss's female. Down in Antarctica, Adelie penguin chicks huddle together in creches. When a parent returns from fishing, it leads its twins on a comical steeplechase - sadly there's only enough for one, so the winner gets the meal. Two months later and the chicks are fully feathered apart from downy Mohican hairdos - they're ready to take their first swim - reluctantly though, as it seems penguins are not born with a love of water! And with good reason - a leopard seal explodes from the sea and pulls one from an ice floe, a hunting manoeuvre that has never been filmed before. As winter approaches and everyone has left, the giant emperor penguin arrives and makes an epic trek inland to breed. The mothers soon return to the sea leaving the fathers to hold the eggs and endure the coldest winter on earth.